Effects of the comminution rate and microbial contamination of particles in the rumen on in situ estimates of protein and amino acid digestion of expeller palm kernel and rapeseed meal

Abstract

The lack of k(c) and microbial correction as well as CP-based results leads to considerable overestimations in the protein use of both feeds. Digestion aggravates the lysine deficiency of EPK but has global positive effects in the absorbed profile of RSM.

Effects of correcting in situ ruminal microbial colonization of feed particles on the relationship between ruminally undegraded and intestinally digested crude protein in concentrate feeds

“…Then, the residues were pooled for each wether before CP analyses to determine IED of RUP. Additional details on ruminal and intestinal incubations, ruminal transit, ruminal degradation models, solid adherent bacteria isolation, microbial colonization, calculations and analytical procedures have been summarised previously . Mean results of k c and k p rates, ruminal microbial contamination with crude protein, RUP, its IED and IDP were also reported in the previous studies, as well as in Table .…”

“…These composite samples were analysed for crude protein (CP) to determine RUP values and also incubated through the intestine in mobile nylon bags to establish intestinal digestibility values. To avoid errors in the correction of the ruminal microbial colonization of the intestinal undigested samples, these incubations were performed after a 10‐day resting period from the ruminal study to eliminate the N enrichment in the digesta. Mobile bags were randomly inserted through the duodenal cannula at a rate of one bag every 15 min (eight bags per wether and day), recovered from the faeces and processed as indicated for ruminal incubations.…”

Amino acid availability in ruminants of cereals and cereal co‐products

“…Wethers were fed with a 2:1 (w/w) chopped oat hay/concentrate diet starting 10 days before the experimental period. Additional details on the animals and diets have been published previously . The protein and AA compositions of tested feeds are given in Table .…”

“…Then, after a 10 day resting period to eliminate the N enrichment in the digesta, a study of the intestinal digestion of the ruminal undegraded fraction (RU) of these feeds was performed using mobile nylon bags that were introduced through the duodenal cannula and recovered in the faeces. All details on these procedures have been published previously . Effective estimates for AA of both RU and its intestinal digestibility (IED) were obtained from composite samples representative of the total rumen outflow of undegraded feed as proposed by Arroyo and González .…”

“…Therefore the resultant values do not consider either the undegraded AA flowing before this fixed time or those flowing after it due to subsequent ruminal protein degradation. In addition, the feed rumen residence has usually been under‐evaluated by considering only the rate of particle outflow from the rumen ( k p ) and not the time used in the process of particle conditioning necessary for this escape, which is represented by the particle comminution rate ( k c ) . Finally, in many of these studies the microbial contamination of feed particles in the rumen was not corrected in ruminal and intestinal estimates, in spite of the fact that this contamination may be important …”